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Träfflista för sökning "WFRF:(Olerud Claes) srt2:(2000-2004)"

Sökning: WFRF:(Olerud Claes) > (2000-2004)

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  • Cornefjord, Michael, et al. (författare)
  • Posterior atlanto-axial fusion with the Olerud cervical fixation system for odontoid fractures and C1-C2 instability in reumathoid arthritis
  • 2003
  • Ingår i: European spine journal. - : Springer Science and Business Media LLC. - 0940-6719 .- 1432-0932. ; 12:1, s. 91-96
  • Tidskriftsartikel (refereegranskat)abstract
    • In posterior C1-C2 fusion, traditional wire fixation gives poor stability. The bone quality is often insufficient to provide the competent structural bone graft that is required, and the introduction of sublaminar wires is somewhat dangerous. The stability is markedly improved by adding transarticular screws, but the drawbacks of structural bone graft and sublaminar wires remain. The C1 claw of the Olerud Cervical Fixation System improves C1-C2 fixation without relying on structural bone graft or compromising the spinal canal. The aim of this study was to evaluate radiological healing and possible complications in a consecutive series of C1-C2 fusions from our department operated with the C1 claw device. Twenty-six patients (14 women) with a mean age of 73 (range 37-93) years were included. The diagnoses were odontoid fracture in 18 patients, rheumatoid instability in 6, and odontoid non-union and os odontoideum in 1 each. The patients were followed clinically and with plain radiographs for an average of 15 (range 3-27) months. There were no neurological or vascular complications, and no secondary displacements or reoperations in the series. Twenty patients followed for 6-27 months were radiographically healed. Six patients died from unrelated causes 1-38 months postoperatively. Three of these patients had no radiographs later than the postoperative control, one had a healed odontoid fracture but resorbed bone graft at 8 months, while the remaining two patients were not healed, but showed no signs of healing disturbance at the time of death. On the basis of the findings of this study, posterior C1-C2 fusion with the Olerud Cervical Fixation System seems promising. No serious complications related to the surgical procedure were encountered. The stability of the implant obviates the use of a solid bone block as a graft and still allows a high frequency of fusion healing.
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  • Henriques, Thomas, 1957- (författare)
  • Biomechanical and Clinical Aspects on Fixation Techniques in the Cervical Spine
  • 2003
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The present work is analyzing the general biomechanical aspects of fixation techniques in the upper and lower cervical spine along with clinical implications.The in vitro biomechanical properties of five different posterior atlanto-axial fixation techniques are compared. They provided for either a one, two or three-point fixation between atlas and axes. A new device, the C1 claw was biomechanically tested, which allow for fixation without the need for a structural bone graft. The three-point reconstructions indicated superior biomechanical properties compared to all others.The new C1 claw device was clinically evaluated in a series of 26 patients treated with a posterior C1-C2 fusion. There were no clinical or radiological failures in the series, Twenty-one patients out of twenty-three with any length of follow up either showed a solidly healed fusion or a healed fracture. Distractive flexion (DF) injuries in the lower cervical spine treated with anterior plate alone were analyzed with respect to healing rate and complications in a consecutive series of 36 patients. Results indicated that DF injury stage 1 and 2 according to Allen and Ferguson healed without complication, whereas DF injuries stage 3 had a high frequency of failure, needing an additional posterior fixation. The in vitro biomechanical properties of four different fixation techniques for a distractive flexion injury stage 3 were analyzed. The result indicated that anterior plate alone for fixation of a DF injury stage 3 is insufficient supporting the clinical finding in the previous study.Adjacent level motion was analyzed following a one segment fusion in the lower cervical spine. Motion was found to increase in adjacent levels possibly contributing to accelerated degeneration.
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  • Henriques, Thomas, et al. (författare)
  • Biomechanical comparison of five different atlantoaxial posterior fixation techhniques
  • 2000
  • Ingår i: Spine. - 0362-2436 .- 1528-1159. ; 25:22, s. 2877-2883
  • Tidskriftsartikel (refereegranskat)abstract
    • STUDY DESIGN:Five different reconstructions of the atlantoaxial complex were biomechanically compared in vitro in a nondestructive test.OBJECTIVES:To determine whether non-bone graft-dependent one-point fixation affords stability levels equivalent to three-point reconstructions.SUMMARY OF BACKGROUND DATA:Previous investigations have demonstrated that three-point fixation, using bilateral transarticular screws in combination with posterior wiring, provide the most effective resistance to minimize motion around C1-C2. However, placement of transarticular screws is technically demanding. Posterior wiring techniques affording one-point fixation have failure rates of approximately 15%, with failure considered to be secondary to structural bone graft failures. One-point, non-bone graft-dependent fixations have not been tested.METHODS:Eight human cervical specimens, C0-C3 were loaded nondestructively. Unconstrained three-dimensional segmental motion was measured. The reconstructions tested were two one-point fixations, one two-point fixation, and two three-point fixations.RESULTS:Under axial rotation two and three-point reconstructions provided better stiffness than the one-point reconstructions (P < 0.05). During flexion-extension, higher stiffness levels were observed in one- and three-point fixations when compared with the intact spine (P < 0.05). In lateral bending no significant differences were observed among the six groups, although the trend was that reconstructions including transarticular screws provided greater stability than one-point fixations.CONCLUSION:The current findings substantiate the use of three-point fixation as the treatment of choice for C1-C2 instability. [l: atlantoaxial fixation, biomechanics, cervical spine, instability, spinal instrumentation, transarticular screws]
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  • Henriques, Thomas, et al. (författare)
  • Distractive flexion injuries of the subaxial cervical spine treated with anterior plate alone
  • 2004
  • Ingår i: Journal of Spinal Disorders & Techniques. - 1536-0652 .- 1539-2465. ; 17:1, s. 1-7
  • Tidskriftsartikel (refereegranskat)abstract
    • The clinical and radiographic effect of anterior plate fixation alone was evaluated in 36 consecutive patients with distractive flexion (DF) injuries in the lower cervical spine. Mean follow-up time was 15 months. The aim of the present study was to determine whether anterior plate fixation alone provides sufficient stability when treating DF injuries in the cervical spine. Solid union was seen in 6 of 6 patients with stage 1 injury and in 15 of 17 patients with stage 2 injury. In the patients with stage 3 injury, 7 of 13 of the anterior fixations failed. These failures occurred mainly among the patients with severe neurologic injuries. We believe these findings substantiate the use of anterior plate alone for DF injuries at stage 1 and 2 but disqualify anterior plate fixation alone for DF injuries at stage 3, with neurologic injury present.
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  • Henriques, Thomas, et al. (författare)
  • Letter to the editor
  • 2001
  • Ingår i: Spine. - 0362-2436 .- 1528-1159. ; 26:21, s. 2405-
  • Tidskriftsartikel (populärvet., debatt m.m.)
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  • Sandén, Bengt, et al. (författare)
  • Hydroxyapatite coating enhances fixation of loaded pedicle screws : a mechanical in vivo study in sheep
  • 2001
  • Ingår i: European spine journal. - : Springer Science and Business Media LLC. - 0940-6719 .- 1432-0932. ; 10:4, s. 334-9
  • Tidskriftsartikel (refereegranskat)abstract
    • Loosening of the pedicle screws with subsequent non-union or loss of correction is a frequent problem in spinal instrumentation. In a clinical pilot study, coating of pedicle screws with plasma-sprayed hydroxyapatite (HA) resulted in a significant increase of removal torque. An experimental study was performed to investigate the effects of HA coating on the pull-out resistance. Thirteen sheep were operated on with destabilising laminectomies at two levels, L2-L3 and L4-L5. Two instrumentations with four pedicle screws in each were used for stabilisation. Uncoated screws (stainless steel) or the same type of screws coated with plasma-sprayed HA were used in either the upper or the lower instrumentation in a randomised fashion. Four sheep were examined immediately after the application of the screws, three sheep at 6 weeks and four sheep at 12 weeks. Two sheep were euthanised early due to complications. The pull-out resistance was recorded in two HA-coated and two standard screws in each animal. The maximum pull-out resistance was higher for the HA-coated screws at 0 weeks (P< 0.02) and at 12 weeks (P<0.01) when compared to the uncoated screws, while there was no significant difference between the groups at 6 weeks. We believe that the higher pull-out resistance for HA-coated screws at 0 weeks was mainly caused by differences in surface roughness, while the difference at 12 weeks was due to a favourable bone reaction around the HA-coated screws. At 12 weeks, the average stiffness was significantly higher for the HA-coated screws, while there was no significant differences in stiffness between the two screw types at 0 and 6 weeks. Energy to failure was significantly higher for coated screws when compared to the uncoated screws at all three time points. HA coating improves fixation of loaded pedicle screws, with increased pull-out resistance and reduced risk of loosening.
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  • Resultat 1-10 av 14

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